Many companies and other organizations operate computer networks that interconnect numerous computing systems to support their operations, such as with the computing systems being co-located (e.g., as part of a local network) or instead located in multiple distinct geographical locations (e.g., connected via one or more private or public intermediate networks). For example, data centers housing significant numbers of interconnected computing systems have become commonplace, such as private data centers that are operated by and on behalf of a single organization, and public data centers that are operated by entities as businesses to provide computing resources to customers. Some public data center operators provide network access, power, and secure installation facilities for hardware owned by various customers, while other public data center operators provide “full service” facilities that also include hardware resources made available for use by their customers.
Some large provider networks implement a variety of storage services, such as services that implement block-level devices (volumes) or objects that can be modeled as arbitrary bit buckets accessible via respective URLs. However, a number of applications running at data centers of a provider network may still face limitations with respect to their use of some of the more common storage-related programmatic interfaces, such as various industry-standard file system interfaces. Some industry-standard file systems may have been designed prior to the large-scale deployment of network-accessible services, and may therefore support consistency models and other semantics that are not straightforward to implement in distributed systems in which asynchronous computational interactions, failures of individual components and network partitions or networking-related delays are all relatively common.
Distributed implementations of file systems and at least some other services may also have to deal with more complex workload balancing problems than, for example, have to be handled with respect to web-services applications relying on stateless protocols such as HTTP. Connections established from client devices to the components of such services may sometimes persist for long durations, with each connection being used for many different requests and responses. The rates at which requests are received via such a persistent connection, and the amount of data typically transmitted per request, may vary substantially over time. Especially in provider network environments handling tens of thousands of concurrent users, managing diverse and time-varying requirements for persistent connections may present a non-trivial challenge.
While embodiments are described herein by way of example for several embodiments and illustrative drawings, those skilled in the art will recognize that embodiments are not limited to the embodiments or drawings described. It should be understood, that the drawings and detailed description thereto are not intended to limit embodiments to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope as defined by the appended claims. The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. As used throughout this application, the word “may” is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include,” “including,” and “includes” mean including, but not limited to.